. >> 438 trees will be brought in from new york, pennsylvania and virginia, in hopes of creating tranquility in the middle of a brusling city. like a little oasis. >> the trees will rise so high that they create a beautiful canopy along the plaza. it's meant to create a peaceful environment to remember those who were lost. >> reporter: and in the heart of the world trade center site, a memorial museum. those of us who were here, will never forget those images. some of them were quite graphic. how do you go about determining what you're going to put on display? >> what happened was tragic and gruesome and -- painful isn't quite the right word. took thousands of lives. and you shouldn't sugar-coat what happened. this was an attack on freedom. not just on new york. not just on america. it was an attack on you and your right to vote and to play and to say what you want to say. and there's nothing -- no easy ways to say this. >> reporter: a continuing work of progress. the committee hopes to have the three-quarters of the site done by the tenth anniversary of 9/11. the reflecting pools, the large